The present invention relates to a bus coupling circuit between a data transfer device (bus) and at least one data transmitter and a data receiver as subscribers, with each subscriber including a bidirectional driver with direct voltage splitting means disposed between the driver and the bus to simultaneously constitute a working impedance for the driver, each driver having a hysteresis.
Such a bus coupling circuit is disclosed in "Regelungstechnische Praxis," [Regulatory Practice], Volume 25, 1983, No. 10, pages S61-S64, and No. 10, pages S69 and S70. In the bus coupling circuit disclosed there, a bus receiver has a hysteresis in order to suppress superposed noise signals.
Subscribers, e.g. data transmitters or data receivers, which are in communication with one another by way of a common bus, have driver circuits as interfaces. If a subscriber or an interface has a short circuit, the entire bus is often unusable. German Patent No. DE 3,433,150 discloses an interface arrangement composed of optocouplers which, if there are faults at the optocouplers due, for example, to a short circuit, prevent blockage of the connection between driver and data input by means of a control circuit associated with the optocouplers.